* hb_ot_layout_feature_get_characters
* hb_ot_layout_feature_get_name_ids
However HarfBuzz currently doesn't expose an API for retrieving the actual
information associated with NameId from the `name` table and that should be
done separately.
For the API tests, output the test programs at $(TOP_BUILDDIR) so that
the freshly-built DLLs will be available for the test programs. For
those that are run through the Python wrapper scripts, use
${PYTHON_EXECUTABLE} instead of plain 'python' in case the Python
interpreter is not in the PATH.
